The goal of the proposed Phase I research is to determine the feasibility of a fast dual path system for respiratory gas analysis. Applications for respiratory gas analysis in health care and physiological assessment and numerous and important, including the measurement of metabolism, lung ventilation efficiency, and patient monitoring. This research proposes development of a system that incorporates a unique method of oxygen analysis based on paramagnetism coupled with an acoustic method to determine carbon dioxide for any given level of oxygen. Essential to the proposed research is development and implementation of high speed pneumatic switching to rapidly interchange test and ambient gas in each transducer (paramagnetic and acoustic), thus providing exceptional stability. The resulting Phase I prototype will be evaluated for dynamic response, linearity, stability of baseline, and stability of scale. It is anticipated that the resulting respiratory gas analyzer will have a response time of <75 ms, and will be capable of breath-by-breath analysis. The proposed development will lead to a new generation of respiratory gas analyzers exhibiting superior performance together with significant cost savings. The estimated cost of the final O2/CO2 analyzer is between $750 - $1,000. PROPOSED COMMERCIAL APPLICATION: Respiratory gas analysis is widespread in the health care environment and physiological research. Oxygen and carbon dioxide analyzers are commonly found as stand-alone analyzers or combined in metabolic measurement systems or anesthetic monitors. Thousands of respiratory gas analyzers are sold each year, and there has been little progress in the critical sensing technologies over the past few years. The commercial potential of the proposed development is significant primarily for the high level of performance coupled with significantly reduced cost.